Just out of curiosity, in what way do you think the trains are a bit spartan?
Good question actually, but I got more of a commuter train feeling than Intercity when I looked at video. But the vinyl seats feel very much like a commuter train. Also lack of coat hooks and no seat back pockets. And do the seats recline? I have the feeling they don't.
Also, the bright colours might add to it, but that is probably just a cultural thing. I really liked the interior DanielB posted, maybe it appeals to my Scandinavian sense of minimalism more?